These teachings relate generally to digital cellular telecommunications systems, protocols and layers and, more specifically, to the evolving third generation (3G) digital cellular systems providing packet data flows between mobile stations and the wireless network.
The following abbreviations are herewith defined.
Reference can also be made to 3GPP TR21.905, V4.4.0 (2001-10), Third Generation Partnership Project; Technical Specification Group Services and System Aspects; Vocabulary for 3GPP Specifications (Release 4).
In GPRS the RLC/MAC layer link between the MS and the network is called a Temporary Block Flow (TBF). In the first releases of GPRS and EGPRS only one TBF could be allocated for a MS. As a result all of the data targeted to a given MS must be sent through the same TBF. At least one disadvantage of this approach is that different applications that can be concurrently running in the MS, and that must share the same TBF, can interfere each other, thereby degrading the expected QoS.
Also, the single TBF may transfer data only in one RLC mode, i.e., in Acknowledge (ACK) mode or unacknowledge (UNACK) mode.
Furthermore, in the case where the RLC mode changes between two consecutive LLC PDUs (PDCP PDUs), the existing TBF has to be released and a new TBF has to be established in the different RLC mode. As can be appreciated, the need to release and then re-establish the TBF can result in user-perceivable and objectionable delays in user data transmission.
It has been proposed to provide a capability to allocate a plurality of TBFs per each MS. The assumption has been, thus far, that the multiple TBF functionality is possible in the Iu mode, as the TBFs can be mapped on Radio Bearers (RBs) and further Radio Access Bearers (RABs) in the CN side (via the Iu interface). Recently some interest has been expressed in providing the multiple TBF functionality as well when the MS is operating in the traditional A/Gb mode. However, in this case the TBF mapping is required to be done in a different way, as significant differences exist between the Iu and the A/Gb interfaces.
As such, the inventors have realized that a need has arisen to provide a mapping mechanism for multiple TBFs between the RLC/MAC layer and the higher layers, when operating in the GERAN A/Gb mode. This need was not fulfilled prior to this invention.
The foregoing and other problems are overcome, and other advantages are realized, in accordance with the presently preferred embodiments of these teachings.
The mapping described herein is beneficially used for the case where it is desired to provide a plurality of TBFs in one direction with one MS operating in the GERAN A/Gb mode.
A method is disclosed for transferring data between a mobile station and a wireless communications network. The method includes generating a plurality of data packets and sending at least one data packet through a first Temporary Block Flow and at least one other data packet through a second Temporary Block Flow, where the first Temporary Block Flow is distinguished from the second Temporary Block Flow by information sent in or with the data packets. When multiple TBFs exist, the first is created and the next one or more TBFs are created using an existing TBF (either an UL or a DL TBF). When transferring data via a TBF, the mobile station and network do not require information regarding the existence of other TBFs, so long as the mobile station and network are able to correctly associate a received packet to the correct TBF based on information received with the packet (e.g., RLC data block).
Also disclosed is a wireless communications system, in the preferred embodiment a GSM/EDGE Radio Access Network system, that includes a Logical Link Control layer of a mobile station and a Logical Link Control layer of a Serving General Packet Radio Service Support Node that are coupled together, where the Serving General Packet Radio Service Support Node and a Base Station System are coupled together through a Gb interface. The system operates for establishing and operating a plurality of Temporary Block Flows for transferring Packet Data Units in either an uplink or a downlink direction between the Logical Link Control layer of the mobile station and the Logical Link Control layer of the Serving General Packet Radio Service Support Node. At any given time there may exist only UL TBF(s), only DL TBF(s), or a combination of UL and DL TBFs.
The system operates at a level of the Logical Link Control layer and a Radio Link Control layer for distinguishing Packet Data Units belonging to a first Temporary Block Flow from Packet Data Units belonging to a second Temporary Block Flow based on information associated with each Packet Data Unit, and maps the Packet Data Units into the appropriate one of the first Temporary Block Flow or the second Temporary Block Flow based on the information. In various embodiments the information is contained in a Packet Data Unit header, or it is derived from information sent with the Packet Data Unit. The information can include Service Access Point Identifier information carried in an address field of each Logical Link Control frame, or the information can include Quality of Service information. The information may be Packet Flow Context information that reflects specific Quality of Service values. The information may also be embodied as Radio Link Control Acknowledge mode information and Radio Link Control Un-Acknowledge mode information. In a further embodiment the information can include Flow Identifier information that is inserted into each Packet Data Unit.
Also encompassed by the teachings of this invention is the case where a tunnel is established between the Serving General Packet Radio Service Support Node and the Base Station System, and all data sent via the tunnel is relayed to one TBF.
In each direction there are from zero to N TBFs. When zero TBFs exist, then one must establish the first TBF in the desired direction when it is needed. The teachings of this invention provide a mechanism for defining, based on certain information, if a new TBF is required, or if an existing TBF can be used to transfer a given LLC PDU.